The Yokogawa EJXC40A Digital Remote Sensor (DRS) Differential Pressure System is a specialized pressure measurement solution designed for applications where the two differential pressure measurement points are physically separated. Instead of using a conventional oil-filled capillary system, the EJXC40A uses two digital pressure sensors connected by dedicated DRS communication cable.
The system consists of a primary sensor on the high-pressure side and a secondary sensor on the low-pressure side. The two sensors measure their respective pressures and communicate through the DRS cable, allowing the system to calculate and transmit differential pressure. The maximum DRS cable length is 45 m, making the system particularly useful for large tanks and remote process connections.
A major advantage of the EJXC40A is its ability to reduce temperature-related errors associated with conventional capillary systems. In tall tanks, for example, process connections can be separated by significant distances and exposed to different ambient temperatures. Oil-filled capillaries can experience thermal effects that influence the differential pressure measurement. The DRS architecture replaces these capillaries with electronic signal wiring, helping minimize this source of measurement error.
The system is especially suitable for tall tank level measurement. Outdoor tank farms may also experience direct sunlight on one process connection while the other remains shaded, creating a temperature difference between the two sides. The EJXC40A measures pressure locally at each sensor and compensates for ambient temperature effects, helping improve level measurement stability.
The EJXC40A uses Yokogawa's DPharp digital sensor technology. The DPharp sensor is an active digital sensing technology with built-in monitoring capabilities. Yokogawa also incorporates a patented real-time reverse signal check to verify signal processing and calculation integrity.
The system can provide multiple process variables, including differential pressure, high-side pressure, high-side sensor temperature, low-side pressure, and low-side temperature. This additional information provides greater visibility into the measurement system and can support troubleshooting and process monitoring.
The EJXC40A provides approximately ±0.056% of span accuracy, 250 ms response time, and ±0.1% of URL long-term stability over 10 years. Its standard output is 4–20 mA with HART digital communication.
The system also supports signal characterization, allowing the 4–20 mA output to be customized for nonlinear process relationships. Yokogawa describes applications such as tank strapping and flow measurement where the relationship between pressure input and the desired output is not linear. Up to 31 characterization points can be used.
Key Features
- Digital Remote Sensor (DRS) Differential Pressure System
- Yokogawa DPharp digital sensor technology
- Two remote pressure sensors for high-side and low-side measurement
- Dedicated DRS communication cable
- Maximum DRS cable length of 45 m
- Approximately ±0.056% of span accuracy
- 250 ms response time
- ±0.1% of URL long-term stability over 10 years
- 4–20 mA output with HART digital communication
- Measures differential pressure as the primary variable
- Provides high-side and low-side pressure information
- Provides high-side and low-side sensor temperature information
- Reduced temperature effects compared with oil-filled capillary systems
- Suitable for tall tank level measurement
- Helps minimize errors caused by differential ambient temperatures
- Signal characterization with up to 31 points
- DPharp active sensor technology
- Patented real-time reverse signal check
- Rugged transmitter construction
- NEMA 4X / IP66 / IP67 housing protection
- Dual-seal construction certified to ANSI/ISA 12.27.01
- Exida SIL 2 / SIL 3 certification according to applicable configuration
- Suitable for remote differential pressure measurement
Measurement Variables
The EJXC40A DRS system can provide multiple measurement variables, including:
- Differential Pressure
- Engineering PV
- Primary Variable %
- Output Current
- High-Side Pressure
- High-Side Sensor Temperature
- Low-Side Pressure
- Low-Side Sensor Temperature
This multi-variable architecture provides additional information for process monitoring and troubleshooting.
Typical Applications
- Tall tank level measurement
- Large storage tank level measurement
- Tank farms
- Outdoor storage tanks
- Differential pressure measurement with remote process connections
- High-pressure fluid measurement
- Liquid level measurement
- Flow measurement
- Steam flow measurement
- Gas flow measurement
- Liquid flow measurement
- Density measurement
- Oil and gas processing
- Petrochemical plants
- Chemical processing
- Refining
- Large process vessels
- Applications where conventional capillaries are affected by temperature
